Soft Palate in Male Dromedary

History

There is no doubt that the most impressive aspect of the rutting behavior of the male dromedary is the frequent exteriorization of the soft palate (also known as Dulaa or Dulla) accompanied by the characteristic gurgling sound. The soft palate is also exteriorized whenever the animal is irritated and this behavior has been associated with aggressiveness and danger in popular literature and tales (Figure 1.33). This phenomenon, known in different parts of the world where the dromedary is reared, has attracted a lot of interest from scientists and lay people to try to understand the anatomical structure and mechanism of distention of the soft palate.^{(26, 40)}
 

Exteriorization of the soft palate is not seen in either the Bactrian camel or the llama. The majority of researchers agree as to the non-functioning diverticulum of the female dromedary and that this is an anatomic peculiarity of the male.⁽³³⁾

An attempt to scientifically describe this anatomical feature of the dromedary was made in the early part of the 19^th century (Savi cited by Dorandi²⁰). This author described the dulaa as a loose extension, corresponding to the uvula in man and other domestic animals, over 1 foot in length, hanging from the lower surface of the soft palate. Exteriorization of the soft palate was explained by the mechanical action of gas eructed from the stomach. A more comprehensive review was offered by Dorandi⁽²⁰⁾ who described the structure as "A vesica buccal is". Others have given this structure the name of 'vesica palatina' because it arises from the oroventral part of the soft palate and is located immediately behind the isthmus faucium.⁽⁷⁾

Morphology

According to Lesbre⁽⁴¹⁾ the soft palate measures 25 cm although other authors reported values ranging from 30 to 35 cm.⁽⁴⁰⁾ From either side of the free end of the soft palate, a well developed posterior pillar extends to the beginning of the esophagus, where they meet on its dorsal surface. The soft palate is attached dorsally and is free in its ventral aspect with its surface folded when it is not distended. The position of the muscles of the soft palate is similar to that in other domestic animals. These are well-developed, especially the palatinus muscle.

The lateral surfaces are in contact with the anterior part of the pharynx. The oral part is free and situated against the posterior part of the dorsum and the root of the tongue. From the posterior part of the dulaa a fold of mucous membrane extends backwards along the median line of the soft palate.⁽⁷⁾

The fixed part of the soft palate lies on the horizontal palatine bone and is loosely attached to the underlying sub-mucous tissue. The root of the tongue is connected to the soft palate by the anterior pillars. The palatine surface is then folded onto itself and proceeds posteriorly to reach the palatinus muscle and is closely attached to the ventral surface of this muscle along its length. Small pink glands are found between the layers of the mucous membrane of the diverticulum of the soft palate. These glands open on both surfaces of the diverticulum by very small, short ducts.⁽³³⁾

Microscopic examination of the dromedary soft palate shows a different structure from that of other domestic animals. On both surfaces of the wall of the diverticulum, stratified epithelium is present separated by a thick layer of areolar tissue containing small areas of mucous glands.⁽³³⁾

Mechanism of distention

Many authors have attempted to study the mechanism of distention and exteriorization of the soft palate in the dromedary. It was stated that the soft palate is pushed upward to approach the nasal membrane (transverse septum) which forms a valve. Simultaneously, air is forced out from the lungs and enters the 'cul de sac'. The air which is trapped in the 'cul de sac' extends the septum to reach the soft palate and complete plugging of the posterior nares. Thus, air can only pass through the isthmus faucium where it becomes concentrated in the middle part of the dulaa. The latter becomes twisted, forming with the tongue and the anterior pillars a structure resembling an inflated sac which projects outside the mouth. On the other hand, Lombardini⁽⁴²⁾ stated that the soft palate is first raised when air issuing from the glottis forces the soft palate upward and anteriorly toward the pharynx, thus closing the passage between the latter and the guttural cavities (posterior nares). He also suggested that, even if this narrow passage remains free, most of the air will still be directed toward the mouth, and consequently, the soft palate. The most complete study of the mechanism of distention of the soft palate was offered by Arnautovic and Abdel Magid.⁽⁷⁾ These authors showed that attempts to blow air through natural openings - esophagus, anterior and posterior nares, opening of mouth, Eustachian tube - and the openings of the glandular projections on the surface of the dulaa, fail to distend it. It is only when the anterior nares are tightly closed and air is blown through the trachea, that the dulaa is distended.⁽⁷⁾ The soft palate should first be raised to prevent access of air to the posterior nares.^{(7, 42)} This is done by contraction of its muscles, which pushes the soft palate upward so that the folds of mucous membrane on the respiratory surface of the former, together with the transverse septum, form a closing valve. Escape of air from the diverticulum into the buccal cavity is prevented by crossing of the folds of mucous membrane of the dulaa and the anterior pillars of the tongue. Therefore, the soft palate is distended merely by air forced from the lungs.

References

1.    Abdel-Raouf, M„ M. R. F. El-Bab. and M. M. Owaida. 1975. Studies on Reproduction in the Camel (Camelus dromedarius) V. Morphology of the Testis in Relation to Age and Season. J. Reprod. Fert. 43:109-116.
2.    Abdel-Raouf, M., and M. M. Owaida. 1974. Studies on reproduction in camels. IV. Gross changes in the morphology of the testis in relation to age and season. Assuit Vet. Med. J. 1:215-223.
3.    Abou-Ahmed, M. M„ A. A. Seida. A. M. Ghallab, S. T. Ismail, and A. B. Elwishy. 1988. Effects of Age and Season on Weight and Some Biochemical Attributes of the Accessory Genital Glands of the One-humped Male Camel (Camelus dromedarius). Zuchthyg. 23:26-32.
4.    Akingbemi, B. T., and T. A. Aire. 1991. Testicular dimensions in sperm reserves in the camel (Camelus dromedarius) in Nigeria. Bull. Anim. Hlth. Prod. Afr. 39:121-123.
5.    Ali, H. A.. K. A. Moniem. and M. D. Tingari. 1976. Some histochemical studies on the prostate, urethral and bulbourethral glands of the one-humped camel (Camelus dromedarius). Histochemical Journal. 8:565-578.
6.    Ali. H. A.. M. D. Tingari, and K. A. Moniem. 1978. On the morphology of the accessory male glands and histochemistry of the ampulla ductus deferentis of the camel (Camelus dromedarius). J. Anat. 125:277-292.
7.    Amautovic, I., and A. M. Abdel Magid. 1974. Anatomy and mechanism of distension of the dulaa of the one-humped camel. Acta anat. 88:115-124.
8.    Badawy, A. B. A.. R. S. A. Ragab, and H. I. Youssef. 1982. Histological and biochemical observations on the accessory reproductive glands of castrated camels. J. Egypt. Vet. Med. Assoc. 42:113-120.
9.    Bravo, P. W., and L. W. Johnson. 1994. Reproductive Physiology of the Male Camelid. Veterinary Clinics of North America: Food Animal Practice. 10:259-264.
10.    Carrera, M., and E. Pachero. 1970. Biopsia testiculare en alpacas. Proc. 1st Cov. Camelidos Sudam. (Auquenidos). Puno, Peru, 101-103.
11.    Casas, P. J. H., F. M. San Martin, and A. M. Copaira. 1962-63. Aspectos histologicos del testiculo de la alpaca, Lama pacos. Rev. Fac. Med. Vet. (Lima). 18-20:223-238.
12.    Chen. B. X.. and Z. X. Yuen. 1984. Reproductive Pattern of the Bactrian Camel. In: Cockrill. W.R. (ed.) The Camelid, an all-purpose animal, Scand. Inst. Afric. Studies, Uppsala Sweden: 364-386.
13.    Collazos, V. G. D. 1972. Estudio de la irrigacion superficial del pene y prepucio de la alpaca, Lama pacos. B.S. Thesis, Fac. Med. Vet., Univ. Nac. Mayor San Marcos, Lima: 1-20.
14.    Curasson, G. 1947. Le Chameau et ses maladies. Vigot, Paris.
15.    Degen. A. A., and D. G. Lee. 1982. The male genital tract of the Dromedary (one-humped) camel (Camelus dromedarius) gross and microscopic anatomy. Zentralbl. Veterinearmed. 11:267-282.
16.    Delhon, G., and L. von Lawzewitsch. 1994. Ductus Epididymidis Compartments and Morphology of Epidiymal Spermatozoa in Llamas. Anat. Histol. Embryol. 23:217-225.
17.    Delhon, G., C. Zuckerberg, I. von Lawzewitsch, E. Larrieu, R. Oporto, and R. Bigaztti. 1983. Estudio citologico de las gonadas de guanaco Lama guanicoe, Macho, en las estudios prepuperales, sexualmente maduros y seniles. Rev. Fac. Cienc. Vet. 1:47-60.
18.    Delhon, G. A., and I. von Lawzewitsch. 1987. Reproduction in the Male Llama (Lama glama), a South American Camelid I. Spermatogenesis and Organizations of the Intertubular Space of the Mature Testis. Acta Anat. 129:59-66.
19.    Djang, K. T. F.. B. A. Harun, J. Kumi-Diaka, H. I. Yusuf, and M. G. Udomah. 1988. Clinical and Anatomical Studies of the Camel (Camelus dromedarius) Genitalia. Theriogenology. 30:1023-1031.
20.    Dorandi. 1936. II cammello: storia natirale, anatomia, fisiologica, zootecnica patologia. Biblioteca agraria coloniale. Firenze (Italia), Institute agricolo coloniale italiano, 1936, 856p. dulla,.
21.    El-Jack, A. H. 1980. The anatomy of the male genital system of the one-humped camel (Camelus dromedarius). Anat. Histol. Embryol. 9:92.
22.    El-Jack. H. A. 1970. On the anatomy of the male genital system of the one-humped camel (Camelus dromedarius). M. V. Sc. thesis, University of Khartoum.
23.    El-Wishy, A. B. 1988. Reproduction in the Male Dromedary (Camelus dromedarius): a Review. Animal Reproduction Science. 17:217-241.
24.    El-Wishy, A. B„ A. M. Mobarak, and S. M. Fouad. 1972. The accessory genital organs of the one-humped male camel (Camelus dromedarius). Anat. Anz. Bd. 131:1-12.
25.    El-Wishy. A. B.. and A. A. Omar. 1975. On the relation between testes size and sperm reserve in the one-humped camel (Camelus-dromedarius). Beitrage Trop. Landwirtsch. Veterinarmed. 13:391-398.
26.    Fahmv. M. F. A., and H. D. Dellman. 1968. Studies on the microscopic anatomy of the oral cavity of Camelus dromedarius. J. Vet. Sci. UAR. 5:45-51.
27.    Fahmy. M. F. A., and A. N. George. 1967. A study on the development of 8-10 months foetal testis of the camel (Camelus dromedarius). J. Vet. Sci. U.A.R. 4:63-68.
28.    Flores, R. F. 1970. Estudio histologico del testiculo de alpacas aparentemente inaptas para la reproduccion. B.S. Thesis, Fac. Med. Vet.. Univ. Nac. Mayor San Marcos. Lima: 1-29.
29.    Fouad. S. M.. A. M. Mobarak. and M. A. Aly. 1979. Micromorphology of the arteries of the penis of the one-humped camel (Camelus dromedarius). Indian J. Anirn. Sci. 49:377-379.
30.    Fowler. M. E. 1989. Medicine and Surgery of South American Camelids. Ames, Iowa, Iowa State University Press.
31.    Fowler. M. E.. DVM. 1994. Reproduction in the Male Llama &. Alpaca. In. Symposium on me health and disease of small Ruminants, Kansas City. Missouri. 56-57.
32.    Frielander, M., A. Rosenstrauch. and E. Bedrak. 1984. Leydig Cell differentiation during the Reproductive Cycle of the Seasonal Breeder Camelus dromedarius'. An Ultrastructural Analysis. General and Comparative Endocrinology. 55:1 -11.
33.    Hegazi. A. E. H. 1949. The Soft Palate of the Camel. The British Veterinary Journal. 105:325-328.
34.    Hussein. I. A. 1980. Micromorphological and histochemical studies on the seasonal changes of the testis of the adult one-humped camel (Camelus dromedarius). M. V. Sc. Thesis, Cairo Univ. Egypt.
35.    Ismail. S. T. 1979. Factors affecting sperm production in the one-humped camel (Camelus dromedarius). M. V. Sc. Thesis. Cairo Univ., Egypt.
36.    Ismail, S. T. 1982. Studies on the testis and epididymis of the one-humped camel (Camelus dromedarius). Ph.D. thesis Cairo Univ., Egypt.
37.    Ismail. S. T. T. 1988. Reproduction in the Male Dromedary. Theriogenology. 29:1407-1418.
38.    Johnson. L. W. 1989. Llama Reproduction. Veterinary Clinics of North America: Food Animal Practice. 5:159-182.
39.    Lee. D. G.. and K. Schmidt-Nielsen. 1962. The skin. sweat glands and hair follicles of the camel (Camelus dromedarius). Anat. Rec. 143:71-94.
40.    Leese, A. S. 1927. A Treatise on the One-humped Camel in health and disease. Hayres & Son Maiden Lane, Stamford. Lincoln Shire.
41.    Lesbre, M. F. X. 1906. Recherches Anatomiques Sur les Camelides. Arch. Mus. Nat. VIII.
42.    Lombardini. 1879. Recerche sui cammelli. Pisa. Italia, Tipografia T. Nistrie et. Co.
43.    Mimram, R. 1962. Les glandes occipitales du dromadaire. Cahier Faculte des Sciences, Rabat 1: 11-42.
44.    Mobarak. A. M.. A. B. El-Wishy, and M. F. Samira. 1972. The Penis and Prepuce of the One-humped Camel (Camelus dromedarius). Zbl. Vet. Med. A. 19:787-795.
45.    Moment, K. A.. M. D. Tingari, and E. KLinzel. 1980. The fine structure of the boundary tissue of the seminiferous tubuie of the camels (Camelus dromedarius). Acta anat. 107:169-176.
46.    Navaro. 1971. Estudio de la inervation espinal periferica de los genitales externos de la alpaca macho Lama pacos. B.S. tesis, Fac. Med. Vet. Univ. Nac. Mayor San Marcos (Lima), Peru. 1-25.
47.    Osman. A. M., and E. A. El-Azab. 1974. Gonadal and epididymal spemt reserve in the camel (Camelus dromedarius). J. Reprod. Fertil. 38:425-430.
48.    Osman, D. I. 1986. The Intratesticular Excurrent Ducts of the Camel (Camelus dromedarius). Animal Reproduction Science. 10:47-60.
49.    Osman. D. I.. K. A. Moniem. and M. D. Tingari. 1976. Studies on the testis of the camel (Camelus dromedarius). Histochemical Journal. 8:579-590.
50.    Osman. D. I.. K. A. Moniem, and M. D. Tingari. 1979. Histological observations on the testis of the camel, with special emphasis on spermatogenesis. Acta anat. 104:164-171.
51.    Osman, D. I., and L. Ploen. 1986. Fine Structure of Sertoli Cells in the Camel (Camelus dromedarius). Animal Reproduction Science. 10:37-46.
52.    Osman. D. I., and L. Ploen. 1986. Spermatogenesis in the Camel (Camelus dromedarius). Animal Reproduction Science. 10:23-36.
53.    Osman. D. I., M. D. Tingari, and K. A. Moniem. 1979. Vascular supply of the testis of the camel (Camelus dromedarius). Acta Anat. 104:16-22.
54.    Owaida, M. M. 1973. Study of the seasonal changes in the morphology of the testes of the camel (Camelus dromedarius) with reference to the changes in relation to age. M. V. Sc. Thesis, Assuit Univ., Egypt.
55.    Pacheco Ibanez. 1968. Biopsia testicular en alpacas. B.S. Thesis, Fac. Med. Vet.. Univ. Nac. Tec. Altiplano. Puno: 1 -54.
56.    Perk, K. 1962. Seasonal changes in the glandula bulbo-urethralis of the camel. Bull. Res. Counc. Israel. !0E:37-44.
57.    Purohit. M. S.. and B. Singh. 1958. The poll Glands in Camel. The Indian Veterinary Journal. 35:295-298.
58.    Ruiz. 1970. Biopsia testicular en alpaca mediante el uso de la aguja de Vim-Silverman. B. S. Thesis, Fac. Med. Vet., Univ. Nac. Mayor San Marcos. Lima: 1-22.
59.    Said. A. H.. and L. B. Youssef. 1966. Urethrotomy in the Camel. .1. Vet. Sci. U.A.R. 3:15-20.
60.    Singh. U. B.. and M. B. Bharadwaj. 1978. Anatomical, histological and histochemical observations and changes in the poll glands of the camel (Camelus dromedarius) Part III. Acta anat. 102:74-83.
61.    Singh.    U.    B..    and    M.    B.    Bharadwaj.    1978. Histological and histochemical studies on the testis of camel (Camelus dromedarius) during the various seasons and ages - Part II. Acta anat. 101:280-288.
62.    Singh.    U.    B..    and    M.    B.    Bharadwaj.    1978. Morphological changes in the testis and epididymis of camels (Camelus dromedarius). Acta anat. 101:274-279.
63.    Singh,    U.    B..    and    M.    B.    Bharadwaj.    1980. Histological studies    on    the    testicular seminal
pathway and changes in the epididymis of the camel (Camelus dromedarius) - Part IV. Acta anat. 108:481-489.
64.    Smith. C. L.. A. T. Peter, and D. G. Pugh. 1994. Reproduction in Llamas and Alpacas: A Review. Theriogenology. 41:573-592.
65.    Smuts. M. M. S., and A. J. Bezuidenhout. 1987. Anatomy of the Dromedary. Clarendon Press, Oxford:230 pp.
66.    Steel. J. H. 1890. A Manual of Diseases of Camel and his management and uses., 1st ed. Lawrence Asylum Press, Madras.
67.    Sumar, J. 1983. Studies on Reproductive Pathology in Alpacas. MS Thesis. Dept Obstet and Gynaec., College of Vet Med, Swedish Univ of Agric Sci,. Upsala.
68.    Taha. A. A. M.. and A. B. Abdalla. 1980. Observations on the Structure of the poll Glands of the Dromedary. Acta Veterinaria (Beograd). 30:247-252.
69.    Tayeb, M. A. F. 1951. L'appareil genital male du Chameau. Rev. elevage Med. Vet. Pays Trop. 5:203-212.
70.    Tayeb. M. F. 1946. The anatomy of the genital organs of the camels, male and female. M. V. Sc. Thesis, 1st Univ.. Cairo. Egypt.
71.    Tingari. M. D., and M. A. George. 1984. Studies on the poll glands of the one-humped camel in relation to reproductive activity. II. Ultrastructural observations. J. Anat. 139:463-474.
72.    Tingari. M. D.. and K. A. Moniem. 1979. On the regional histology and histochemistry of the epididymis of the camel (Camelus dromedarius). J. Reprod. Fert. 57:11-20.
73.    Tingari. M. D.. K. A. Moniem. and E. Kiinzel. 1979. Observations on the Fine Structure of the Testicular Interstitial Cells in the Camel (Camelus dromedarius). Quarterly Journal of Experimental Physiology. 64:39-45.
74.    Tingari. M. D.. B. A. Rahma, and S. H. M. 1984.
Studies on the poll glands of the one-humped camel in relation to reproductive activity. 1. Seasonal morphological and histochemical changes. J. Anat. 138:193-205.
75.    Tingari. M. D.. A. S. Ramos, E. S. E. Gaili. B. A. Rahma, and A. H. Saad. 1984. Morphology of the testis of the one-humped camel in relation to reproductive activity. J. Anat. 139:133-143.
76.    Urquieta, B., R. Cepeda, J. E. Caceres. L. A. Raggi, and J. R. Rojas. 1994. Seasonal variation in some
reproductive parameters of male vicuña in the High Andes of northern Chile. Journal of Arid Environments. 26:79-87.
77.    Urquieta, B.. and J. R. Rojas. 1990. Studies on the reproductive physiology of the vicuña (Vicugna vicugna). In: Livestock Reproduction in Latin America, Proc. of the Final Research Coordination Meeting of the FAO / IAEA /ARCAL. Vienna. 1990; 407-428.
78.    Volcani, R. 1957. Seasonal sexual activity shown in male camels. Israel state agriculture department bulletin.
79.    Williamson, and Payne. 1978. An introduction to animal husbandry in the tropics. Tropical series in Agriculture, London, Great Britain, Longman, 744 pages.