Ultrastructural study of embryonic and post-hatching development in the pineal organ of the chicken (brown leghorn, Gallus domesticus)

Abstract

The pineal organ of the chicken was investigated electron microscopically during embryonic and post-hatiching development with special regard to photosensory and secretory features. Throughout the developmental period both pinealocytes and supporting cells, of which the pineal parenchyma is composed, were rich in ribosomes, granular endoplasmic reticulum and mitochondria, but lacked agranular endoplasmic reticulum. The outer segments of pinealocytes barely showed formation of lamellar structures (disks) at the 17th and 21st day of incubation. Before and after hatching the follicular lumen was ofter filled with amorphous material presumed to be derived from outer or inner segments. By 15 days after hatching thw whorl-like structures were occasionally connected to bulbous outer segments, and their relation appeared similar to that of the adult. Mitochondria disappeared from the inner segments after 21 days of incubation. Dense core vesicles (about 80-120 nm in diameter), regarded as secretory granules, appeared first at the 10th day of incubation in the supranuclear region of the pinealocyte. With the extending of basal processes the dense core vesicles gradually migrated into these processes, attained maximum number one month after hatching and increased further in the adult; they are located both around the Golgi apparatus and in the basal process. These results provide evidence that secretory activity is maintained from embryonic stages to adulthood.

Immunoelectron-microscopic investigation of the subcellular localization of pinopsin in the pineal organ of the chicken

“…For this purpose, conventional transmission and scanning electron microscopy has been used (cf. Oksche and Vaupel-von Harnack 1966;Oksche and Kirschstein 1969;Oksche et al , 1972Boya and Zamorano 1975;Omura 1977;Calvo 1978, 1980;Matsuo 1984, 1988;Möller and Möller 1990). In these studies, typical photoreceptor cells with regular comb-like arrangements of outer segment membranes have not been identified, although basic sensory structures such as bulbous cilia with associated lamellar complexes have been observed (Menaker and Oksche 1974;Vollrath 1981).…”

Role of tissue interaction between pineal primordium and neighboring tissues in avian pineal morphogenesis studied by intraocular transplantation

“…Developmental studies on the avian pineal gland have mostly been based on morphological observations at the light (Renzoni 1970;Calvo and Boya 1978) and electron microscopic (Omura 1977;Calvo and Boya 1979) levels, and include descriptions of the expression patterns of genes such as rhodopsin (Robinson et al 1995), HIOMT (Grechez-Cassiau et al 1995) AA-NAT (Herichova et al 2001) and the transcription factors. Only a limited number of studies aiming to clarify the mechanisms involved in pineal development have been reported (Cameron 1903;Bargmann 1943;Holmgnen 1965).…”

Evolution of photosensory pineal organs in new light: the fate of neuroendocrine photoreceptors

“…This has been interpreted as evidence that the avian pineal is transformed from a pineal organ to a 'pineal gland' during ontogeny (Sato 2001), a notion which implies loss of photoreceptor characteristics. However, according to Omura (1977) photoreceptor-like structures gradually become more abundant (or easier to detect) with increasing age in the pineal organ of the brown leghorn chicken. In the Japanese quail, there is an initial decrease in numbers of paraboloids and regular stacks of lamellae after hatching, accompanied by an increase in the numbers of synaptic ribbons, but during later development more developed lamellar whorls appear in the follicular lumen (Ohshima & Hiramatsu 1993).…”