Zusammenfassung
Es wird die Entwicklung des Hühnchens im Ei vom 1. Tag bis zum Ausschlüpfen dargestellt und beschrieben. Dabei werden die täglichen Entwicklungsschritte in gleichen Präparationsstufen, die schematisch erläutert sind, wiedergegeben.
Summary
The development of the chick within the egg
The development of the chick within the egg from the first day until hatching is described and illustrated. The stage of development for each day in incubation is illustrated in a similar way and is explained with the aid of diagrams.
Résumé
Le développement du poulet dans l'oeuf
Le développement embryologique du poulet dans l'oeuf est représenté et décrit depuis le premier jour jusqu'au moment de l'éclosion. Les progrès observés chaque jour sont indiqués sur les mêmes plans de préparation et sont expliqués schématiquement.
Resumen
El desarrollo del embrión en el huevo de gallina
Se expone y describe el desarrollo del embrión de pollo desde el primer día hasta la eclosión. Para ello, reprodúcense los avances evolutivos diarios en iguales escalas preparatorias, que se ilustran esquemáticamente.
An ultrastructural study of the boundary tissue of the seminiferous tubule of the camel reveals that it consists of three lamellae; inner fibrous, inner cellular and outer cellular. The inner lamella is subdivided into two homogeneous layers enclosing a third one that contains collagenous fibres and fine filaments. The inner cellular lamella consists of several layers of myoid cells; each layer is separated from the adjacent layer by homogeneous material and varying amounts of collagen. The outer cellular lamella consists predominantly of fibrocytes together with some fibroblasts and scattered collagen.
Testicular interstitial cells of the camel are polygonal in shape with abundant smooth endoplasmic reticulum (SER) occurring as a network of tubules. Elements of a welldeveloped Golgi complex are seen in many parts of the cytoplasm. There is a moderate number of mitochondria with predominantly lamellar cristae and dense intramitochondrial granules. Lipid droplets vary in size and number from cell to cell. Lysosomal bodies are commonly encountered in the cytoplasm. Other cytoplasmic constituents include microfilaments, peroxisomes, a few pathches of rough endoplasmic reticulum and occasional glycogen particles.
The functional significance of these observations is discussed in relation to comparative observations on other vertebrates as in relation to histochemical findings on camel testis. There is sufficient evidence to indicate that the interstitial cells in the camel testis resemble interstitial cells of other vertebrates.
Letdig cells during the non‐breeding season possess abundant lipid droplets, large lysosomal bodies together with narrow cisternae of SER, i.e. features of inactivity. Maximal activity is seen during the rutting season and it is suggested that this activity correlates with the of seminiferous epithelium and accessory sex glands.
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