Ovary of the southern hairy-nosed wombat (Lasiorhinus latifrons): its divergent structural organisation.

The organisation of the ovarian interstitial tissue in the southern hairy-nosed wombat Lasiorhinus latifrons was investigated. Unlike in most other marsupials, the outer cortical region of the ovary contains abundant luteinised interstitial tissue that largely occurs in discrete lobules, many of which contain a localised area of non-cellular, highly eosinophilic and periodic acid-Schiff-positive material. The findings suggest that the latter arises from the zona pellucida that surrounded the oocyte in growing follicles and that the luteinised interstitial tissue thus developed from transformed theca interna of degenerated atretic follicles. It is hypothesised that this tissue synthesises and secretes progestogens, which may result in the long, and variable, oestrous cycle length that has been found to occur in this species.

Whole-body heat exposure induces membrane changes in spermatozoa from the cauda epididymidis of laboratory mice.

This study was carried out to determine if exposure to hot environmental temperatures had a direct, detrimental effect on sperm quality. For this the effect of whole-body heat exposure on epididymal spermatozoa of laboratory mice was investigated. C57BL/6 mice (n = 7) were housed in a microclimate chamber at 37 degrees C-38 degrees C for 8 h per day for three consecutive days, while control mice (n = 7) were kept at 23 degrees C-24 degrees C. Cauda epididymal spermatozoa were obtained 16 h after the last heat treatment. The results showed that sperm numbers were similar in the two groups (P = 0.23), but after heat treatment, a significant reduction in the percentage of motile sperm was present (P < 0.0001). Membrane changes of the spermatozoa were investigated by staining with phycoerythrin (PE)-conjugated Annexin V, which detects exteriorization of phosphotidylserine from the inner to the outer leaflet of the sperm plasma membrane, and 7-aminoactinomycin D (7-AAD), which binds to the sperm nucleus when the plasma membrane is damaged. The percentage of spermatozoa showing positive staining with Annexin V-PE or 7-AAD or both, was significantly higher (P < 0.05) in heat-exposed mice compared with controls. These results show that whole-body heat exposure to 37 degrees C-38 degrees C induces membrane changes in the epididymal spermatozoa of mice, which may lead to apoptosis.