The length of gestation is between 160 and 180 days (Olmedo et al., 1985; Furley, 1985). Singletons, and frequently twins (40%) are born of Cuvier's gazelles (Olmedo et al., 1985). The twins are of same sex in 69% and were thus (statistically) considered to be dizygotic. A singleton female neonatal death we observed weighed 2,000 g and had a 73 g placenta with 30 cotyledons and a 21 cm long umbilical cord.

3) Implantation

The placenta of this immature gestation shown here, the only one that has been studied so far of this species, was implanted in the right horn and extended into the left uterine horn. The uterus contained a single fetus. No term placenta has been studied as yet. Inasmuch as this species has some general (genetic) similarities to the slender-horned gazelle, the reader is also referred to that chapter.

Three term placentas have since become available that will be described below.

4) General Characterization of the Placenta

Initially I had the opportunity to examine one implanted placenta of a female that died from peritonitis following a penetrating trauma. The entire specimen weighed 1,400 g and had an immature, 300 g, 19 cm female fetus with placenta inside. The placenta was implanted primarily in the right horn, however, some cotyledons extended into the left horn. The allantoic sac was lateral and as large as the amnionic cavity. It was filled with light yellow urine. The placenta had approximately 70 cotyledons that varied from 1 to 2 cm in width.

Six new specimens have since become available. Two were from term, normal deliveries and weighed 250 and 100 (twin) g. One measured 59 cm in length and was 35 cm wide. There were 70 cotyledons, arranged in four rows. They measured from 1 to 4 cm in diameters and were 0.4 cm thick. The umbilical cord measured 9 cm in length, had four blood vessels and it was frayed, as is the case in most gazelle specimens. The second term placenta from a twin gestation (one was stillborn) had 46 cotyledons. The stillborn twin whose placenta was not available weighed 2.35 kg. The placenta of the liveborn twin conformed in every respect to the other term placenta studied. Yet another singleton placenta had 60 cotyledons. Finally, an additional placenta from a set of twins is shown below. Twin A had a 190g placenta with 70 cotyledons; twin B had a 110 g placenta with 55 cotyledons. That twin died at the age of one day and seemed to be too small for a normal term gestation. . In March of 2004 a stillborn twin (1,720 g with 100 g placenta and 34 cotyledons) was associated with a live-born fetus whose placenta weighed 190 g and had 78 cotyledons.

This is a polycotyledonary, epithelio-chorial placenta.

Measurements of Cuvier gazelle placentas

8) Extraplacental membranes

The vascularized allantoic sac was large and filled with urine. It lay lateral to the amnion as an elongated structure, bounded by uterus on one side and amnion on the other. There were no hippomanes. The amnion was very thin and had numerous tiny black dots over its surface. Histologically, the latter are composed of foci of pigmented squamous metaplasia. The epithelium was very thin. Between the cotyledons were areolar regions with actively secreting endometrial glands and some debris in between the endometrium and the columnar trophoblast that covers the allantochorion.

10) Endometrium

No true decidua is being formed.

11) Various features

The endometrium beneath the implanted cotyledon is not infiltrated by trophoblast and appears histologically fibrous.

12) Endocrinology

No studies have been performed. The fetal ovaries were very small and unstimulated.

13) Genetics

The Cuvier's gazelle has 32 chromosomes in females, and 33 chromosomes in males. This is due to the Robertsonian translocation of the X-chromosome to an autosome (Kumamoto & Bogart, 1984). These authors also found minor banding variations among several animals. Vassart et al. (1995) further delineated the cytogenetic arrangements of gazelle chromosomes, using the caprine banded karyotypes as the presumed ancestral form. These two groups of authors both found the karyotypes to be similar to that of Gazella leptoceros, despite their significantly different phenotypes. Hybrids are unknown.

Inbreeding ("depression"), however, may be a problem in this species. Roldan et al. (1998) and Gomendio et al. (2000) studied the ejaculatory semen quality of this species and that of the less endangered G. dama. Their findings suggested that, while the quality of Cuvier's gazelle semen was inferior, it had not yet reached devastating proportions.

14) Immunology

No studies are known to me.

15) Pathological features

This animal died from peritonitis due to intestinal perforation. It also had gastric ulcers and massive whipworm infestation. Toxoplasmosis has been reported by Stiglmair-Herb (1987), and a variety of helminthes were found in animals captive in Spain (Ortiz et al., 2001a). These authors worked with a large number of animals (58) and experimented with various anthelminthic regimes (Ortiz et al., 2001b).

16) Physiologic data

No studies are known to me other than the collection of hematologic and biochemical data by Casado et al. (1991).

17) Other resources

Cell lines of numerous animals are available from CRES at San Diego Zoo by contacting Dr. Oliver Ryder at: oryder@ucsd.edu.

18) Other remarks - What additional Information is needed?

Term placentas, their weights, and dimensions are still unknown. It would also be of interest to know if hybridization with slender-horned gazelles occurs and whether they would be fertile.

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.

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