Dimensional guide to harvesting the radius for orofacial reconstruction.

OBJECTIVE: To provide an accurate harvesting guide to maintain the maximum possible safe dimensions of the radius for orofacial reconstruction using the osteocutaneous radial forearm free flap. MATERIAL AND METHOD: Two hundred radii of 100 adult formalin-embalmed cadavers (52 males, 48 females) were measured. RESULTS: The mean minimum circumference of the radius measured between the pronator teres and brachioradialis insertions was 41.0 +/- 4.3 mm. At this point, the mean medio-lateral diameter was 13.4 +/- 1.6 mm. The mean of the maximum harvested length of the radius between the pronator teres and brachioradialis insertions was 81.3 +/- 10.4 mm. On the average, the maximum harvested length of the radius was 34.9% of its total length. The minimum medio-lateral diameter of the radius was consistently 1-5 mm less than 40% of its minimum circumference. There was no significant dimensional difference between sides but gender difference existed in all measurements (p < 0.001), except the maximum harvested length of the radius. CONCLUSION: The present study may be helpful to guide reconstructive surgeons for safer harvesting of the radius using the osteocutaneous radial forearm free flap to repair orofacial defects.

The development of the rabbit eye.

Serial sections of the rabbit embryos measuring 4-14 mm. were carefully studied to compare the developing eye with 36 somites chick embryos and 10-15 mm. pig embryos. The eyes of the 4-5 mm. rabbit embryos were at an earlier stage than those of the 36 somites chick embryos, but at about the same stage as the fifth-week human embryos. At this stage, the optic cups had already formed but some of the lenses had incompleted double fusion. The eye of the 12-14 mm. rabbit embryos were somewhat identical to the 15 mm. pig embryos and can be compared to the sixth week human embryos. At this stage the optic cups were divided into the outer pigment and inner nervous layers; the lens was characterized by a thinner anterior lens epithelium and the longer posterior lens fiber. The mesenchyme surrounding the optic cups of this stage showed a slight condensation to from the vascular and fibrous coats of the eyeball. The rabbit embryos of 4-14 mm. were more suitable for use as laboratory models in studying eye development than of the pig embryos since the latter were no longer available for slide preparation.

The development of the ear of rabbit embryo.

The ear consists of three parts which are different origin but function as one unit. The internal ear originates from the surface ectoderm covering the lateral sides of myelencephalon at the fourth week. This ectoderm thickens to from the otic placode and then invaginates to form the otocyst and splits from the surface ectoderm. The otocyst or otic vesicle divides into 2 parts, the ventral cochlear and the dorsal utricular portions. The cochlear gives rise to the saccule and the cochlear duct while the utricular portions gives rise to the uteicle, semicircular ducts and endolymphatic duct. These epithelial structures so formed are known as the membranous labyrinth. The bony labyrinth and the perilymphatic space originate from the mesenchy otic capsule. The middle ear, consisting of the tympanic cavity and the auditory tube, are lined with epithelium of the endodermal origin of the first pharyngeal pouch. The ear ossicles, the malleus and incus are derived from the first and the stapes from the second arch cartilages. The external auditory meatus develops from the first pharyngeal cleft, while the tympanic membrane originates from the mesenchyme between. In order to understand ear development, pig and chick embryos were used in the laboratory studies. Since the pig embryos are presently not available, this compared the ear development of the pig and rabbit embryos, which indicate that the ear of the pig and rabbit develob in the same manner and the rabbit embryos can be used in the future instead of pig embryos for studying ear development.

Anatomical variation course of the lateral femoral cutaneous nerve as it exits the pelvis in Thais from the central region.

The aim of this study was to examine in detail the course and location of lateral femoral cetaneous nerve (LFCN) as it emerges from the pelvis in Thais. The anatomy of the LFCN was studied through the dissection of 107 halves of formalin-embalmed Thai cadavers ranging in age from 37 to 94 years. The LFCN is formed by the union of posterior divisions of ventral rami of the second and third lumbar spinal nerves (L2 – L3). The site at which the nerve exits the pelvis is quite variable. Depending on the anatomical location which varies from superficial and posterior, to medial and deep, to anterior superior iliac spine (ASIS) and origin of the sartorius muscle, five different types as identified by Aszman et all1 were confirmed : type A, posterior to the anterior superior iliac spine across the iliac crest (1.86%); type B, medial to the anterior superior iliac spine and ensheathed in the inguinal ligament (9.34%); type C, medial to the anterior superior iliac spine and ensheathed in the tendinous origin of the sartorius muscle (46.72%); type D, medial to the anterior superior iliac spine located in the interval between sartorius muscle and iliopsoas muscle deep to the inguinal ligament (40.18%); type E, medial to the anterior superior iliac spine, deep to the inguinal ligament, overlying the iliopsoas fascia, and contributing the femoral branch of genitofemoral nerve (1.46%). The majority of the LFCN course and location as it exits the pelvis are type C (46.72%), and type D (40.18%). There is no statistical difference with regard to either gender or side of thigh.

An improved method for whole mount embryo preparations from chick embryos.

Background : Embryology studies require good quality embryonic images. In addition, many teratology studies require the critical gross examination of embryos to determine the exact stage of embryonic development, or the extent of malformations. Objectives : The present study was designed to develop an improved method for preparing embryos. Materials and Methods : Sixty fertilized chicken eggs were divided into 6 groups of 10 and incubated at 38 oC foe various time periods (18, 20, 25, 30, 55, 72 hrs) depending on the developmental stage of the embryos. After incubation, the embryos were removed from the shells and yolk sacs. In each group, 5 embryos were stained using the Mayer’s carmine technique and the remaining 5 embryos were stained using the improved method. By the new method, the embryos were macerated in 3% potassium hydroxide for different length of time before the Mayer’s carmine staining. Results : It was found that the whole mount chick embryos which were stained with Mayer’s carmine after maceration were of better quality than those stained using the routine Mayer’s carmine technique. The new method gave superior preservation, clarity and contrast of the normal embryonic details. Interestingly, the advantage of the new method was clearly noted in the later stage of embryonic development, at the 30-somite and 30-somite stages. Using the routine Mayer’s carmine technique, the development of heart, circulation, and nervous system were not clearly differentiated, since those structures were concealed by soft tissues and/or many structures. In contrast, the new technique facilitated identification and allowed us to understand the whole development process of those structures. Conclusions : The new method improves the visibility of embryonic details normally seen or not seen with the Mayer’s carmine technique. It permits good quality photographs to be produced rapidly and consistently for the standard gross embryo analyses in embryology and teratology.