Ultrastructure of the Pineal Body of the Domestic Chicken, with Special Reference to the Changes Induced by Altered Photoperiods

The authors studied the embryonic development of the pineal gland of the chicken with the electron microscope. The denomination of ‘pinealoblasts’ was given to the undifferentiated cells which form the primitive pineal outline. In the wall of the pineal cavities, the follicular and parafollicular zones were distinguished; these are formed by type A and type B pinealocytes, the B type being much more abundant. The degenerated cells are constant in the pineal throughout its embryonic development, but much more abundant in the early phases.

Section: Discussionmentioning

confidence: 69%

Ultrastructural study of the embryonic development of the pineal gland of the chicken (Gallus gallus)

Calvo

Boya

1979

“…, 1969Collin. , 1971Fujie, 1968;Bischoff, 1969;Ueck, 1970;Boya and Zamorano, 1975]. The function of these ribbons is not known.…”

Section: Discussionmentioning

confidence: 99%

Ultrastructural study of the post-hatching evolution of the pineal gland of the chicken (Gallus gallus)

Boya

Calvo

1980

There is a marked evolution in the ultrastructure of the chicken pineal gland after hatching. The typical large follicular cavities tha tare visible just after hatching disappear with age, giving the pineal a large number of small-caliber cavities which are practically filled by the prolongations of the pinealocytes. This gives the organ an apparently solid aspect. There are still two large cell types in the follicular wall: the A and B pinealocytes, with the B type being considerably more abundant.

“…This cellular type has been regarded as a supporting cell by several authors [Ok sc he and Vaupel von Harnack, 1966;Fujie, 1968;Collin, 1971;Omura, 1977] and also as an ependymal cell [Bischojf, 1969]. The function of mechanical support, if such, must not be very important if we are to judge by the amount of microtubules and microfilaments present in this cellular type.…”

Section: Discussionmentioning

confidence: 99%

Evolution of the pineal gland in the adult chicken

Boya¹,

Calvo²

1979

The structural pattern of the pineal gland in the hen corresponds to a more advanced stage of the evolution which began in an early period of the animal’s life. This evolution corresponds mainly to the transformation of the large follicular cavities into cellular ‘rosettes’. The parafollicular layer disappears from the rosette wall which thus remains with only one row of cells (A and B pinealocytes). The cellular hypertrophy and the great development of the pinealocyte organelles in the adult pineal gland makes us think of this gland as a functionally active organ. This functional activity must have remained during the entire period of the time studied (1–5 years), due to the ultra-structural uniformity found and due to the fact that we could not observe any type of degenerative process in the gland.