Current concepts: the use of immunoperoxidase techniques in mohs micrographic surgery.

Mohs micrographic surgery is used for the removal of certain malignant tumors, both ensuring complete excision by histologic examination of margins as well as minimizing normal tissue loss. Recently, several investigators have incorporated the use of immunoperoxidase techniques to aid in the removal of selected high-risk carcinomas, sarcomas, and melanomas. We describe the basic principles of immunoperoxidase and review recent articles in which immunoperoxidase was used as an adjunct to routine hematoxylin-eosin staining in Mohs micrographic surgery. Additionally, we show examples of selected tumors comparing routine hematoxylin-eosin stains and immunoperoxidase. We believe the use of immunoperoxidase can be of significant value in the removal of certain high-risk tumors. In particular, this technique is useful in "unmasking" malignant cells in areas of dense inflammation, identification of some cases of perineural invasion, identification of pagetoid spread in carcinomas and melanomas, and finally in helping to identify subtle margins in dermatofibrosarcoma protuberans.

Two populations of tyrosine hydroxylase-positive cells occur in the spinal cord of the chick embryo and hatchling.

The existence of tyrosine hydroxylase (TH)-containing neurons in the spinal cord of the chick embryo was investigated by anti-TH immunocytochemistry. Two populations of intensely immunostained cells were observed along the entire extent of the cord, beginning late in chick embryogenesis. One group of TH-positive cells was particularly numerous and found ventral to the central canal. The other group, which was smaller in number, was located along the superficial and lateral border of the dorsal horn of the spinal cord. When examined by the glyoxylic acid histofluorescence technique, cells could be visualized only very infrequently ventral to the central canal, and not at all within the dorsal horn. However, after pretreatment of hatchlings with the catecholamine synthesis precursor L-DOPA, cells ventral to the canal were readily observed by histofluorescence, while the dorsally located cells seldom visualized. Since these populations of TH-positive cells appear to only partially express the catecholaminergic phenotype, these cells may provide a model in which factors regulating the expression of neurotransmitter phenotypes can be examined in neurons of the developing CNS.

Analysis of the change in number of serotonergic neurons in the chick spinal cord during embryonic development.

The existence of serotonin (5-HT)-containing neurons in the spinal cord of the chick embryo was examined by anti-5-HT immunocytochemistry. The first immunoreactive cells were observed in embryos at 7 days of incubation (E7) and were initially located within the floor plate of the early spinal cord. By E9, immunostained cells occurred throughout the length of the spinal cord and were frequently encountered in most transverse sections of the cord. When examined at later embryonic ages of E12, 17 and at hatching (E21 or 22), the 5-HT cells became progressively more difficult to find with the advancing age of the embryos. To determine if this population of spinal cord 5-HT neurons actually diminished during development, a detailed quantitative analysis was undertaken to estimate the number of 5-HT cells in the cord of chick embryos at different ages. The results of this investigation demonstrated that the size of the 5-HT neuronal population rose rapidly from E7 and plateaued (at approximately 3500 neurons) between E9 and E12. As anticipated, the number of 5-HT cells at E17 decreased at all cord levels. Surprisingly, however, the number of spinal cord 5-HT neurons at hatching increased (depending on the cord level) either back to, or above, the counts estimated for the earlier ages of E9 and E12. Therefore, cells expressing the 5-HT phenotype in the spinal cord of the chick embryo persist throughout the period of embryonic development, rather than appear transiently.(ABSTRACT TRUNCATED AT 250 WORDS)