Indian Sambar Deer (Cervus unicolor niger)

Order: Artiodactyla

Family: Cervidae

1) General Zoological Data

In most classifications, Sambar deer belong to the subgenus Rusa.Both are Hindi names for deer. Sambars are widely distributed through India,South-East Asia and many Pacific Islands and have been introduced to Australiaand New Zealand (Wilson & Reeder, 1992). Some of the islands may alsohave sambars that were recently introduced. The subgenus (Rusa) has fourspecies (C. alfredi, C. marianus, C. unicolor, C.timorensis). The German designation often used is "Aristotlehirsch",since the animal was already well-known to Aristotle from West India. Itwas then also designated as being characteristically a six-pointer. In German,these animals are also referred to as "Pferdehirsch" because oftheir long legs. A recent study of mtDNA by Randi et al. (2001) suggeststhat this clade separated from other cervidae around 5 MYA. Nowak (1999)referred to recent electrophoretic findings that have suggested a closerelationship to Axis and Dama deer. Haltenorth (1968) differentiatedthree species, with 18 subspecies. Adult males are larger than females andhave characteristically 6 antler points and long legs. Their weights varyfrom 100-315 kg. Sambars are reported to be more of a browsing than grazinganimal that prefers to live in wooded regions. Newborns weigh around 10kg. The longevity in captivity is at least 24 years and 5 months (Jones,1993).

Because of the availability of this specimen and the large size of its placentalcotyledons, this deer species is treated here separately; other cervid speciesare detailed in a separate chapter, on "Deer species" (see therefor more discussion).

Indian sambar deer group at San Diego Wild Animal Park.

Malayan sambar deer stag at San Diego Zoo.

Malayan sambar hind with fawn at San Diego Wild Animal Park.

2) General Gestational Data

The length of gestation is 8 months or 240 days (Nowak, 1999; Hayssen al.,1993) with usually single offspring. Records of twins exist, but they occuruncommonly (Hayssen et al., 1993). Plotka (1999) referred to studies thatindicate that the length of gestation is 240-270 days.

3) Implantation

I have had the opportunity of studying one pregnant uterus near the end of gestation. This was from a hind that died from intraspecific trauma. The uterus measured 130 cm in length; the female fetus weighed 8.3 kg and had a crown-to-rump length of 66 cm. There were six large cotyledons, three in each uterine horn. The cotyledons weighed from 300 to 320 g (with their caruncle attached) and measured 5 x 9 cm. The uterus is bicornuate and the placenta implants on the three mesometrial caruncles of both horns.

Diagram of typical deer placentome and intercotyledonary space.

4) General Characterization of the Placenta

As other deer species, sambars have only a small number of caruncles and, therefore, cotyledons. This specimen had six cotyledons that were of rather large size. This is thus an "oligo-cotyledonary", epithelio-chorial placenta without invasion into the maternal tissue, much like that of most other cervidae studied (see Hamilton et al., 1960). The cotyledons have a convex shape.

Pregnant uterus of Indian Sambar deer before opening.

Uterus with fetus inside and intact allantoic sac (left). The other uterine horn lies at the right side of the pregnant horn.

Sambar deer fetus within its amnion. The six large cotyledons are labeled, three each occupying each uterine horn.

Implanted cotyledons ("placentomes") of Sambar deer. The fetal surface is left, the uterine tissue is below left.

Implanted cotyledons ("placentomes") of Sambar deer. The fetal surface is left, the uterine tissue is below left.

5) Details of fetal/maternal barrier

The microscopic details of the cotyledonary and arcade structures of the sambar deer placenta are most similar to the other deer species studied. They have been summarized in detail in publications by Sinha et al. (1969) and by Hamilton et al. (1960). Most of this is reviewed in some detail in the other general chapter on "Deer Species" to which the reader is referred. This placenta is mostly remarkable because of the large size of the cotyledons. They are so large that a complete cross section cannot be fitted onto one slide. Binucleate trophoblast are present as in other ruminants; they PAS-positive and one has to assume that they also produce relaxin or lactogen as other ungulates, although that has not been shown for this species. The fetal capillaries course within the trophoblastic cover of the villi.

Structure of the cotyledonary surface. F.V.=Fetal Vessel. V.=Villus. A.P.=Amnionic Plaque (Squamous metaplasia).

Maternal surface of cotyledon. V=Villus. The caruncular extensions (dark) in between the somewhat edematous (autolyzed) villi become very thin.

Villus within the caruncle with binucleate cell (Bi). Note the flat endometrial epithelium and the small capillaries within the surface trophoblastic layer of the villus.

Attachment of villi to the caruncle floor.

6) Umbilical cord

The umbilical cord of this pregnancy measured 7 cm in length, had four blood vessels and a large, patent allantoic duct. The cord was not spiraled. The surface of the umbilical cord had large stretches of massive squamous metaplasia, as shown below. The amnionic epithelium had fine granules on its surface, also consisting of squamous metaplasia. The allantoic duct shown below was lined by urothelium and was empty. It was accompanied by a large number of small blood vessels.

The surface of the umbilical cord has long stretches of keratinized epithelium.

Allantoic duct in the center of umbilical cord with small vessels.

7) Uteroplacental circulation

I know of no studies in this deer species.

8) Extraplacental membranes

The allantoic sac was filled with milky, yellow fluid and had a very thin epithelium. There were no hippomanes. The amnion had many tiny foci of squamous metaplasia. They are composed of cells that were described in detail for the white-tailed deer by Sinha et al. (1970).

9) Trophoblast external to barrier

There is no trophoblastic infiltration of uterus or caruncle.

10) Endometrium

The bicornuate uterine horn has three mesometrially located caruncles in each horn, most similar to that described in detail by Sinha et al. (1969) for white-tailed deer.

11) Various features

No special features were identified.

12) Endocrinology

I have had the opportunity of examining also the fetal testes of sambar deer. Their interstitial cell compartment appears to be completely unstimulated, from which I infer that no fetal gonadotropins are active. The presence of binucleate trophoblastic cells on the villi suggests relaxin or lactogen production during pregnancy (Wooding et al., 1997). Although no specific studies on Rusa are included, Plotka (1999) summarized most of what is known of the endocrine function in cervidae.

13) Genetics

Cooper & Herbert (2001) examined the survival of animals derived from the small introduced population of sambar that now inhabit Australia and New Zealand. Remarkably, a thriving colony of sambar deer was founded by only two animals.

Gray (1972) does not list any hybridization with other species. Putative hybrids with Cervus timorensis (a closely related species) have not been definitely characterized (Dratch & Pemberton, 1991). These authors studied electrophoretic characters of deer species but stated that no Sambar deer had been studied by then.

Their chromosome picture is confusing. Chandra et al. (1967) found an Indian sambar deer from Mysore, India, to have 58 chromosomes. Animals from the Philippines karyotyped by us had 64 or 65 chromosomes. The NF, however, has always been 70, as is the case in most deer species (Hsu & Benirschke, 1973). There is much unresolved confusion of Cervus unicolor and Rusa species that is also evident from the review by Groves and Grubb (1987). Among other remarks, they cited Wang & Du (1982) as having identified the Chinese Cervus (Rusa) unicolor dejeani (cambojensis) as having 2n=62 chromosomes, with NF 70. Halnan (1989) listed the following for Cervus unicolor: 2n= 58, 64/65, 62. Our experience with Cervus unicolor malaccensis is 2n=56; for C. unicolor niger it was 2n=58. A male "Sambar deer" described by Neitzel (1979) from the Berlin Zoo had 2n=60. It is thus apparent that extensive Robertsonian rearrangements have occurred in this subgenus that needs more extensive study of animals with known, precise origin of location. The NF (nombre fondamental - chromosome arms), however, is always 70.

Miyamoto et al. (1990) studied some mtDNA sequences of cervinae and found close relation of muntjacs and sambars.

14) Immunology

I know of no studies in this deer species.

15) Pathological features

With advanced age, sambar deer have developed arthritis that necessitated euthanasia (Griner, 1983). According to the review by Heuschele et al. (1984), Rusa (Cervus timorensis) have been reported to suffer from malignant catarrhal fever.

16) Physiologic data

I know of no studies in this deer species.

17) Other resources

Numerous cell strains of various sambar deer are available from CRES at the San Diego Zoo by contacting Dr. Oliver Ryder at oryder@ucsd.edu.

18) Other remarks - What additional Information is needed?

More endocrine and chromosomal data are needed, especially of what are now considered to be "subspecies". It appears from the various chromosomal studies that some of the "subspecies" have widely divergent chromosome numbers and thus may deserve species ranking. In addition, early gestational stages and descriptions of term delivered placentas would be of interest.

Acknowledgement

The animal photographs in this chapter come from the Zoological Society of San Diego. I appreciate also very much the help of the pathologists at the San Diego Zoo.