Reported morphologies of the ultimobranchial body had varied between researchers: a cluster of mitotic cells, a duct-like structure and a rosette-like cell mass. To clarify the true morphology, we studied tilted horizontal sections of 20 human embryos (crown-rump length 5-18 mm; 4-6 weeks). The sections displayed a ladder-like arrangement of the second to fourth endodermal pouches and, in 5 early embryos we found the fifth pouch attached to the fifth ectodermal groove near the fourth pharyngeal arch artery. The bilateral fifth pharyngeal pouches protruded anterolaterally to form a U-shaped lumen surrounding the arytenoid swelling. The third to fifth pouches were each characterized by a pedal-shaped inferior end. We identified several types of cell clusters as candidates for the ultimobranchial body, but morphologically most of them were, to various degrees, likely to correspond to the blind end of the lower pouch when cut tangentially. Because of the topographical relation to the common carotid artery, a cyst-like structure with a cell cluster seemed to be the most likely candidate of the ultimobranchial body (a common anlage of the thymus and parathyroid). However, we were not able to deny a possibility that a certain plane cutting the pouch end incidentally provided such a cyst-like structure in sections. At any stage, the ultimobranchial body might not appear as a definite structure that is discriminated from others with routine staining. A concept of the ultimobranchial body might be biased by comparative anatomy that shows the ultimobranchial gland in adult birds and reptiles.
The dorsal lingual surface of the grey crowned crane (Balearica regulorum), American flamingo (Phoenicopterus rubber), great egret (Ardea alba), mallard (Anas platyrhynchos), Himalayan monal (Lophophorus impejanus), black-necked stilt (himantopus mexicanus) and green macaw (Ara militaris) were examined by scanning electron microscopy. In the grey crowned crane, the surface of the lingual apex was relatively rough. Many openings of the lingual glands in both lateral regions of the lingual body were observed. The surfaces of many conical papillae were smooth. Many openings of the lingual glands were observed in the region of the lingual root. In the American flamingo, the surface of the lingual apex was relatively smooth. The surfaces of many fang-like and mustache-like structures were smooth. In the great egret, the surfaces of the lingual apex, central part of the posterior lingual body and giant conical papilla were relatively smooth. Many openings of the lingual glands were observed on the lingual root. In the mallard, the surface of the lingual apex was relatively smooth. The thread-shaped and scale-shaped structures were observed on the anterolateral region of the lingual body. The saw-shaped papillae on the posterolateral region of the lingual body consisted of the thread-shaped structure and big processes. In the Himalayan monal, the dorsal surfaces of the lingual apex and body were relatively smooth. The posterior part of the lingual body consisted of several conical papillae. Many openings of the lingual glands were observed on the lingual root. In the black-necked stilt, the surface of the lingual apex was relatively smooth. The dorsal surface of the lingual body was rough to comparison with that of the lingual apex. The posterior part of the lingual body consisted of several conical papillae. In the green macaw, the surface of the lingual apex had many grooves. The posterior part of the lingual body consisted of several conical papillae. These findings indicate a close correlation between the shape of the tongue and the method of food intake, the type of food, and bird’s habitat.
We examined the dorsal lingual surface of an adult eastern grey kangaroo (Macropus gigantues) by scanning electron microscopy. The filiform papillae on the lingual apex and anterior body consisted of a main papilla and secondary papillae. The connective tissue core of the filiform papillae on the lingual apex had several processes. The filiform papillae on the lingual posterior body were thread-like in shape. The connective tissue core of the filiform papillae on the lingual posterior body consisted of many slender processes. The fungiform papillae were round in shape. Three vallate papillae with the apex of the triangle directed posteriorly consisted of a groove and pad. Several conical papillae derived from the posterolateral margin of the tongue where foliate papillae have been shown to be distributed in many other animal species. The surface structure of the tongue in the eastern grey kangaroo resembles that of the red kangaroo.
To examine a common plantar tendinous plate for long flexors of the toe and fingers in human embryos, we observed sections of 10 embryos at 5-6 weeks (crown-rump length or CRL 15-21 mm). The heel or tuber of the calcaneus was underdeveloped in 3 embryos with CRL 15 mm and the talus appeared not to be piled up on the calcaneus but these two bones were arranged along the lateromedial axis. As reported in the hand, we demonstrated, in the deep side of tarsal bones, a common tendinous plate formed by a joining of the flexor halluces longus and flexor digitorum longus tendons. In the tendinous plate, much or less, some connections between tendons seemed to remain even after birth to provide much greater types of tendon anomalies than in the hand. In addition, we postulated a hypothetical change in course of the peroneus longus tendon. In the initial phase, because of the underdeveloped calcaneus, the peroneus tendon might take an almost straight course similar to long flexor tendons. However, at 6 weeks and later, the inferomedially expanding calcaneus beneath the talus was likely to push the tendon to the cuboid bone.
Fetal cruciate ligaments of the knee provide two types of cartilage attachments: to a cartilage fovea or a simple continuation to the perichondrium. To examine a difference in matrix substance between a ligament attachment to the fovea and another attachment to the perichondrium. We histologically observed 12 human fetal femurs in which the posterior (or anterior) cruciate ligament provided a fovea-type (or a perichondrium-type) attachment. Immunohistochemistry of matric substances (aggrecan, versican, tenascin-c) was performed. In the knees, aggrecan was consistently positive in any cartilage, versican was in the joint surface and tenascin-c in the perichondrium. In contrast to the femoral attachment, the anterior and posterior cruciate ligaments consistently continued to the perichondrium at the tibial attachment (versican-, tenascin+). In the femoral condyles, tenascin-immunoreactivity was seen in both of a fovea-type and a perichondrium-type attachments, but versican was not in both. During development of the cartilage fovea, the growing ligament seemed to push the perichondrium into the cartilage and, much or less, the tenascin-positive perichondrium was likely to be involved into the fovea.