The pineal gland of the mole (Talpa europaea L.) II. Ultrastructural variations observed in the pinealocytes during different parts of the sexual cycle

Abstract

Changes of some ultrastructural parameters (paracrystalline structures, Golgi apparatus, secretory granules) in mole pinealocytes were quantitatively studied during the various phases of the sexual cycle. An increase in quantity of paracrystalline structures and of the Golgi appratuses was demonstrated during the period of high sexual activity in male pinealocytes and during oestrus, gestation and lactation in female pinealocytes. Moreover, the appearance of vacuoles in female pinealocytes was observed during pro-oestrus. These results seemto demonstrate close relationship between the endocrine activity of the hypophyseo-gonadal axis and the synthesis of some compounds by the pinealocytes. No increase in the quantity of secretory granules was observed during the various phases of the sexual cycle studied. Key words: pinealocytes, mole, sexual cycle, ultrastructure, paracrystalline structure.

Seasonal changes in testosterone levels and androgendependent organs in male moles (Talpa europaea)

“…Whether there is a rapid response to increasing daylength after this solstice, or a delayed response to decreasing daylength before it, remains to be discovered. Sexual activity coincides with an increase in the activity of the pineal gland, particularly in the number of paracrystalline structures synthesized by pinealocytes (Pevet & Smith, 1975). In addition, the prolactin-secreting cells of the anterior pituitary gland undergo massive hypertrophy during spermatogenesis and achieve maximum development during the phase of testicular involution (Pieters & Herlant, 1972).…”

Generation of the Melatonin Endocrine Message in Mammals: A Review of the Complex Regulation of Melatonin Synthesis by Norepinephrine, Peptides, and Other Pineal Transmitters

“…In vivo variations in the activity of the pineal gland depending on the female sexual cycle have been observed in several species: rat (Quay, 1963;Wurtman et al, 1965;Ozaki et al, 1978), sheep (Cardinali et al, 1974b), mole (Pévet and Smith, 1975), human (Wetteberg et al, 1976;Parry et al, 1990), squirrel (Ellis and Balph, 1976), and pony (Wesson et al, 1979), with no consistent pattern according to the estrous stage. In addition, the effect of large changes in steroid levels following gonadal suppression or steroid injections are not considered to be physiologically relevant.…”

A Light and Electron Microscopic Study of the Pineal Body of the Nutria (<i>Myocastor Coypus</i>)

“…Based upon this fact and similarities in cell shape and location of the nucleus, it is likely that the two types of cells observed reflect different physiological states of the same cell type. The time of year might also be a factor since studies utilizing the golden hamster [Mogler, 1958], sheep [Nesic, 1962], hedgehog [Pevet and Saboureau, 1973], mole [Pevet and Smith, 1975], macaque [Bererhi and Abbas-Terki, 1970] and seal [Cuello and Trarnezzani, 1969] have indicated a seasonal rhythm in pineal morphology and/or histochemistry.…”