Release Of Secretory Products Research Articles

MORPHOLOGIC OBSERVATIONS CONCERNING THE RELEASE AND TRANSPORT OF SECRETORY PRODUCTS IN THE ADENOHYPOPHYSIS.

AbstractThe processes involved in the release of secretory products from the parenchymal cells and the movement of these products into the circulating blood were studied by electron microscopic observations on the adenohypophyses of virgin estrous rabbits. The released secretory products were found in the form of discrete granules, with or without a perigranular membrane, in intercellular spaces, between the plasma membrane and the parenchymal basement membrane, in the perivascular space, in the endothelial cytoplasm, and in the lumen of capillaries. Vesicles containing material which resembled that in the perivascular space were observed in endothelial cells.Interpretation of these observations has led to the proposal of the theory that secretory products of the adenohypophysis may be liberated from parenchymal cells in the following way: by fusion of the perigranular membrane with the plasma membrane (merocrine) or by the detachment of small processes containing secretory granules (“microapocrine”). It is further believed that the discharged products may be transported into circulation in three different manners: by diffusion of dissolved material through the fenestrated endothelium, by active transport of dissolved secretory products by the endothelial cells, or by active transport of intact secretory granules through the endothelial cytoplasm.

DEVELOPMENT AND FUNCTION OF NEUROSECRETORY SITES IN THE EYESTALKS OF LARVAL PALAEMONETES (DECAPODA: NATANTIA)

1. The histogenesis of eyestalk organs in Palaemnonetes vulgaris, P. pugio, P. intermedius, and P. kadiakensis is essentially the same. Palaemnonetes paludosus, having an abbreviated larval development, follows the same sequence of events in a shorter period of time.2. The developing eyestalk of Palaemonetes has two consistent, characteristic features: (a) a single, large, nionopolar, secretory neuron that becomes active during the first larval stage, and (b) a sac-like vacuole in the sensory pore X-organ that appears to be the site of storage and release of secretory products, from the first larval stage through adult life.3. The sensory pore X-organ develops from neuroblasts of the eyestalk ganglia. It appears 5 or 6 days before hatching. It is located dorsally and remains in this position throughout larval development. Secretory droplets appear in the SPX vacuole during the first larval stage. The accumulation of droplets increases throughout larval life.4. The sinus gland is not recognizable until the...