No abstract

No abstract

Ovarian follicular dynamics were determined in adult llamas by ultrasonography and palpation per rectum and hormone analysis (estradiol-17 beta and estrogen conjugates) of plasma and urine. The relationship of gonadotropin secretion to follicular development was determined by the analysis of plasma FSH and LH concentrations. Progesterone analysis of plasma was used to verify or deny the presence of CL. Final follicular development (from 3 mm) averaged 4.8 days, while the duration of the mature follicle (8-12 mm) averaged 5.0 days; regression of the follicle occurred over about 4 days. The development of a subsequent dominant follicle usually began within 2-3 days after onset of regression of the dominant follicle. While several follicles were present at the time of the demise of the dominant follicle, only one follicle continued to develop. The interval between ovarian follicle waves averaged 11.1 days. Dominant follicle activity alternated between ovaries in 81% of the cycles. The occurrence of dominant follicles was evenly distributed between ovaries. While plasma estradiol and estrogen conjugate concentrations were positively associated (p less than 0.05) with follicular activity, urinary estrogen conjugate concentrations best reflected ovarian follicular dynamics (p less than 0.001). Daily FSH concentrations in plasma were not correlated with follicular activity. LH concentrations in plasma were low in all animals throughout the study, indicating estrogen from developing ovarian follicles does not induce the release of LH. Progesterone values were low during the study, indicating that the llama does not spontaneously ovulate, at least under the conditions of this study. In summary, llamas have overlapping ovarian follicle waves that occur at about 11-day intervals.(ABSTRACT TRUNCATED AT 250 WORDS)

The relation of ovarian follicle size to pituitary and ovarian responses to copulation was studied in domesticated South American camelids (llamas and alpacas). Females from each species were divided into four groups according to follicle size: small (4-5 mm), growing (6-7 mm), mature (8-12 mm), and regressing (10-7 mm). The pituitary response to copulation was determined by analysis of LH and FSH concentrations in plasma. The ovarian response to copulation was determined by ultrasonography and by analysis of estrone sulfate (follicular status) and pregnanediol glucuronide (luteal status) concentrations in urine. Females with small follicles (4-5 mm) released less LH after copulation than did those with larger follicles, and ovulation was not induced. Females with growing and mature follicles (7-12 mm) released LH in response to copulation that was adequate to induce ovulation and to initiate normal luteal activity. While copulation-induced LH release in females with regressing follicles was similar to that released in animals with growing and mature follicles, regressing follicles were luteinized instead of being ovulated. The luteal structure formed as a result of luteinization of follicles had a short life span, i.e., 5.1 days. Copulation-induced LH release was significantly higher in llamas vs. alpacas in animals with mature or regressing follicles, but not in those with small or growing follicles. Urinary estrone sulfate and pregnanediol glucuronide concentrations correlated positively with the presence of follicles and corpora lutea, respectively.

Skin biopsy specimens of normal llama skin were examined histologically. Adnexal structures similar to those of most other domestic mammals included epitrichial sweat glands, sebaceous glands and arrector pili muscles. Unique features of normal llama skin included a very thick dermis with marked dierences between super®cial and deep dermis, prominent cutaneous vascular plexuses, unidenti®ed cells with eosinophilic granules within the adventitia of the vascular plexuses, both simple and compound hair follicles, metatarsal glands',`interdigital glands', footpad glands and the absence of eyelid tarsal glands. SheddingLlamas undergo a yearly partial shed, involving primarily the undercoat, but shedding is more pronounced every second year. 4,5 This diers from camels, which normally shed their entire winter coat each summer unless they are equatorial 7 or chronically deprived of drinking water. 8 In llamas, a shorter dense haircoat is present over the convex surface of the pinna, forehead, lateral cheek and distal extremities. The hairs in these areas are more uniform in size. A very short sparse haircoat is present over the muzzle, chin, eyelid, axillae, abdomen, inguinal region, medial thighs,¯anks, perineum, ventral tail and distal extremities. Glabrous skin is present on the concave surface of the proximal pinnae, ear canal, mucocutaneous junctions, teats, metatarsal glands, interdigital glands and footpads.