[Post-natal maturation of the retina in the albino rat. I. The pigment epithelium]. / Maturazione post-natale della retina nel ratto albino: I. L'epitelio pigmentato.

The Authors studied the postnatal development of the retinal pigment epithelium in the albino rat, in order to elucidate its morphological and functional evolution, correlated to the numerous functional roles played in Vertebrates (Scheme 1). At birth, epithelial cells show few cytoplasmic organules and the apical surface provided of small depressions. From the third to the fifth postnatal day the first apical microfolds surround the depressions. From the seventh to the ninth day inner segments develop, whilst the apical surface of the epithelial cells is covered by many finger-like microfolds. During the eleventh postnatal day the buds of the outer segments and many lamellar microfolds can be demonstrated. During the sixteenth day the retina reaches its adult morphology. It is therefore well-evident that birth, similarly to many other Vertebrates, is not the last step, but only a moment, in the development of the retina: this process is completed only during postnatal life, when environmental light is able to stimulate every ocular structure.

[Histochemical aspects of the differentiation of the gastric glands]. / Aspetti istochimici del differenziamento delle ghiandole gastriche

The Authors have studied some aspects of the differentiation of gastric mucosa, during the prenatal and postnatal development in man and mouse. They have demonstrated that in both species the first elements of glandular rudiments can be already recognised, owing to the richness of their mitochondrial store, as parietal cells, where oxireductase activities are already present. The functional differentiation in the membrane of such elements takes place later on: from the point of view of the function the parietal cell can then be considered as completely differentiated. Chief cells, on the contrary, define their morphological and functional characters starting from the fifth month of foetal life. At any rate, at least for the studied characters, the gland store of human gastric mucosa, at birth and in the adult, is exactly alike.