Two main types of cervical mucus have been described during the menstrual cycle: oestrogenic and progestative. Each category shows diverse morphological and functional features from the reproductive point of view. Traditionally, this change has been approached by analysing morphological patterns. In fact, a mesh model has been described for cervical mucus, structurally composed of fibrillar subunits with a parallel orientation, together with another model in a characteristic network shape with canalicular units, but the real model is not clear. The objective of our work was to study the different morphological structures of the mucus, as related to the day of follicular rupture (considered as day 0) determined by ultrasound. Cervical mucus samples were obtained from the cervical canal with an ASPIRETTEtrade mark from day -4 to day +1 of the menstrual cycle. Samples were fixed and dried by critical point. The ultrastructure was examined with scanning electron microscopy. The presence of three types of oestrogenic and one type of progestative cervical mucus was confirmed in this period. Our paper shows different types of ultrastructure in the oestrogenic mucus in relation to ovulation, which would help to understand the interaction between male gametes and cervical mucus in migration through the female genital tract.

Mammalian germ cell apoptosis plays a key role in controlling the correct number of germ cells supported by Sertoli cells during the fi rst wave of spermatogenesis in mammalian puberty. However, little is known about hormonal factors that could infl uence the rate of germ cell apoptosis during puberty or adulthood. In this work we evaluate germ cell apoptosis under hypothyroidism induced by goitrogen propylthiouracil (PTU) during the fi rst wave of spermatogenesis. Neonatally administered PTU promoted a delay in the differentiation of Sertoli cells as evaluated by the expression of clusterin using immunohistochemistry and RT-PCR. Clusterin had different expression levels in control and PTU-treated animals, but under both conditions the highest levels were found in 35-day-old rats. In addition, clusterin displayed a cytoplasmic localization in control testes, but appeared located in the nucleus in PTU-treated animals. The wave of apoptosis (determined by caspase activity and quantifi cation of apoptotic cells) characteristic of the fi rst round of spermatogenesis was delayed by at least 10 days in these animals. The expression levels of proapoptotic genes like BAX or BAD were different between control and PTU-treated rats; although in both groups the highest level was found at the same age (days). Thus our results indicate that the characteristic pubertal apoptotic wave during rat spermatogenesis is delayed in neonatal hypothyroid rats.