Reproduction in the ferret (Mustela furo) I. Uterine histology and histochemistry during pregnancy and pseudopregnancy

Abstract

Similar histological and histochemical changes occur in the uteri of pregnant and pseudopregnant ferrets. The pre-implantation period is characterized by general growth of the tissue and moderate secretory activity. At the time of implantation, the luminal epithelium undergoes hypertrophy and hyperplasia and shows much secretory activity. This area of altered activity sweeps progressively toward the gland fundi and the epithelium behind it becomes greatly enlarged and forms symplasmic masses. Symplasma formation occurs in all regions of the uterus, in contrast to other carnivores where it occiirs only next to trophoblast and in response to uterine trauma.The principal uterine secretions are mucoproteins and glycoproteins. There is some evidence that pseudopregnant uteri, but not pregnant uteri, secrete acid mucopolysaccharides. Glycogen is present in moderate amounts at estrus, declines during the pre-implantation period, and is absent during gestation. A light to moderate diffuse sudanophilia is seen during pregnancy and pseudopregnancy, becoming more pronounced toward the end of the gestation period. Occasional cholesterol crystals are seen in macrophages in the stroma of pregnant, but not pseudopregnant, uteri. Macrophages containing hemosiderin were seen in all uteri examined, being most abundant in estrous and early pre-implantation uteri. Uterine mast cells were abundant at estrus, declined during the pre-implantation period and decreased markedly at the time of implantation. The results are compared with data from other carnivore species.Several features make the ferret well suited for studies in reproductive physiology. There is a well defined breeding season and estrus is easily determined by the degree of vulval enlargement. Since the animals are induced ovulators, the various events of pregnancy can be timed rather accurately. Pregnancy lasts 40-42 days and consists of a relatively long preimpIantation period of 10-12 days and an active gestation period of 30 days. A period of pseudopregnancy which is exactly the same length as pregnancy follows sterile mating. The influence of the amount of daylight on the reproductive cycle has been much exploited in prior studies of the relationship of environment to neural control of reproduction. The basic features of the ferret reproductive cycle were first described by F. H. A. Marshall ('04). Although a more detailed description of the cycle and the histological changes of the reproductive tract during estrus, pseudopregnancy and pregnancy was published by Hammond and AM. J. ANAT., 118: 195-216.

Heterologous anti-progesterone monoclonal antibody arrests early embryonic development and implantation in the ferret (Mustela putorius)

“…Plasma progesterone concentrations in ferrets after passive immuniz¬ ation with heterologous anti-progesterone monoclonal antibody (see Table 1 for details of treatment) Plasma Morphological appearance of the antibody-treated uterus The endometrium of ferrets treated with antibody appeared similar at Day 14 p.c. to that of the preimplantation endometrium reported by Buchanan (1966), and to that of pseudopregnant con¬ trol ferrets in the present study (Wang et al, 1984), and this probably results from an interference with the availability of circulating progesterone for target cell interaction.…”

The Effect of an Intra-Uterine Plastic Device on the Mast Cell Count in the Rat Uterus

“…It has been known for a long time that there is a correlation between the histamine content of a tissue and the mast cell count (Riley & West, 1953). Mast cells have been demonstrated in the uterine tissue of golden hamsters (Harvey, 1964), guinea-pigs (Iversen, 1962), ferrets (Buchanan, 1966) and cows (Likar & Likar, 1964). Changes in the mast cell count at different phases of the oestrous cycle were observed in cows, hamsters and ferrets by the above mentioned workers who found an increase in the mast cell count in the oestrous phase.…”

Morphological, Histological and Immunohistochemical Study of the Rabbit Uterus during Pseudopregnancy

“…This stage characterized by; mucosal folding, glandular formation (endometrial adenogenesis), epithelial proliferation and thickening of the uterine wall [13]. Similar changes were occurred in pseudopregnant ferrets [15] and pregnant marsupials [16]. These changes were due to increased plasma progesterone level [17].…”