Tongue Growth during Prenatal Development in Korean Fetuses and Embryos

BACKGROUND: Prenatal tongue development may affect oral-craniofacial structures, but this muscular organ has rarely been investigated. METHODS: In order to document the physiology of prenatal tongue growth, we histologically examined the facial and cranial base structures of 56 embryos and 106 fetuses. RESULTS: In Streeter's stages 13-14 (fertilization age [FA], 28 to 32 days), the tongue protruded into the stomodeal cavity from the retrohyoid space to the cartilaginous mesenchyme of the primitive cranial base, and in Streeter's stage 15 (FA, 33 to 36 days), the tongue rapidly swelled and compressed the cranial base to initiate spheno-occipital synchondrosis and continued to swell laterally to occupy most of the stomodeal cavity in Streeter's stage 16-17 (FA, 37 to 43 days). In Streeter's stage 18-20 (FA, 44 to 51 days), the tongue was vertically positioned and filled the posterior nasopharyngeal space. As the growth of the mandible and maxilla advanced, the tongue was pulled down and protruded anteriorly to form the linguomandibular complex. Angulation between the anterior cranial base (ACB) and the posterior cranial base (PCB) was formed by the emerging tongue at FA 4 weeks and became constant at approximately 124degrees-126degrees from FA 6 weeks until birth, which was consistent with angulations measured on adult cephalograms. CONCLUSIONS: The early clockwise growth of the ACB to the maxillary plane became harmonious with the counter-clockwise growth of the PCB to the tongue axis during the early prenatal period. These observations suggest that human embryonic tongue growth affects ACB and PCB angulation, stimulates maxillary growth, and induces mandibular movement to achieve the essential functions of oral and maxillofacial structures.

A Study on the Early Development of the Hip Joint in Staged Human Embryos and Fetuses in Korean / 체질인류학회지

The author has studied 33 cases of Korean embryos of Carnegie stage 11 ~23 and 18 cases of fetuses to demonstrate the development of the hip joint. The external feature of the lower extremity was observed by stereoscope and digital camera, and the internal structures were studied by light microscopic observation. The results obtained were as follows: In stage 13 lowerlimb buds were appeared. In stage 17 mesenchymal condensation for femur and hip bone, and one -layered interzone were observed. In stage 18 cartilage models for ilium and ischium were visible. In stage 22 three -layered interzone between the head of femur and hip bone was formed. In stage 23 acetabular labrum and distinct three -layered interzone was visible. In the 9th weeks mesenchymal ligamentum capitis femoris and transverse acetabular ligament are appeared, and acetabular labrum was reacted tracely to trichrome stain. In the 10th week the joint space was formed between the femoral head and hip bone, and shallow depression in acetabulum is found. In the 12th week the articular capsule was directed lateral to acetabular labrum, and numerous blood vessels were found in acetabular fossa and ligamentum capitis femoris, and cartilage canal were developed in femoral neck. In the 14th week cartilage canal was found in middle of femoral head, and synovial fold were developed, and ligamentum capitis femoris was shown strongly positive reaction. In the 16th week cartilage canals were more found, and numerous blood vessels were observed in fovea capitis. In the 18nd week the neck of femur was narrow, and femoral head was lied deeply in acetabulum with acetabular labrum. Consequently the lower extremity of Korean embryos and fetuses was first appeared in stage 13, and hip joint development was started at stage 17. The articular cavity was first formed at the 9th week of development, the acetabulum labrum was developed at stage 23. The mesenchymal ligamentum capitis femoris was appeared at the 9th week. At the same time the transverse acetabular ligament fully encircled the femoral head. The articular capsule has lined the articular cavity at the 12th week, and synovium was formed at the 14th week of development. At the 18th week the hip joint has attained its final shape.

Development of the Shoulder Joint in Staged Human Embryos and Fetuses in Korean / 체질인류학회지

The authors have studied 37 Korean embryos of Carnegie stage 11~23 and 18 fetuses to demonstrate the development of the shoulder joint. The external feature of the upperlimb bud is observed by stereoscope and camera, and the internal structures are studied by microscopic observation. The results obtained were as follows: In stage 12 upperlimb buds were appeared. In stage 17 mesenchymal condensations for humerus and scapula, and glenoid labrum were observed. In stage 19 one-layered interzone between the humerus and scapula was visible. In stage 22 three-layered interzone between the humerus and glenoid labrum was formed. In stage 23 three-layered interzone between the humerus and glenoid fossa of scapula was visible. In the 9th and 10th weeks distinct joint cavity was formed between humerus and glenoid labrum, and tendon of long head of Biceps brachii was attached to supraglenoid tuberosity and glenoid labrum. In the 11th week the joint cavity was formed between the midportion of humerus and glenoid fossa, and tendon of long head of Biceps brachii was more dense. In the 16th week the glenoid labrum was visible as fibrous cartilage, and joint cavity was more widened. In the 20th to 32nd week the shoulder joint was matured with the distinct joint cavity and glenoid labrum time after time.